Liquid Crystal Display (LCD) is the most mature flat-panel display technology at present. For example, mobile phones, digital cameras, video cameras, notebook computers, and monitors, which are commonly used in daily life, are all manufactured by this technology.
However, as the application areas of new technologies expand and people's requirement for the visual appeal of the display becomes higher, a flat-panel display with higher image quality, high definition, high brightness, and low price has become the direction and motivation for the development of the upcoming display technology. A Low Temperature Poly-silicon (LTPS) thin film transistor (TFT) in the flat-panel display, apart from its active driving characteristic, is exactly an important technical breakthrough to achieve the above objectives.
Traditional LTPS TFT, as shown in FIG. 1, includes a glass substrate 101 and a buffer layer 102 arranged on the glass substrate 101. On the buffer layer 102, a poly-silicon layer is formed, which comprises a source electrode arranged in a source region 103, a drain electrode arranged in a drain region 104, and a gate insulating layer GI arranged on a channel region 111. A gate electrode 108 and a passivation layer 109 are formed on the GI layer. The GI layer generally adopts a two-layer composite structure comprising a dielectric layer 105 and a dielectric layer 107, which are generally made from SiO2 and SiNx.
However, the gate insulating layer formed by SiNx and SiO2 suffers from poor surface contact performance and thin film continuity, as well as undercuts when via holes are formed thereon, which means that SiO2 holes are greater than SiNx holes due to a higher etching rate of SiO2 than that of SiNx, thus leading to poor contact performance.
Therefore, in order to solve the above-mentioned problems, it is a major subject of efforts in this industry to provide a method for manufacturing a low temperature poly-silicon thin film transistor which has relatively strong contact continuity, and can effectively reduce the parasitic capacitance and thus improve the response rate of the transistor.